Electrical tension control device for strip processing line



Dec. 13, 1966 Filed Feb. 1. 1963 FOR STRIP PROCESSING LINE A. R FOREMAN ELECTRICAL TENSION CONTROL DEVICE 2 Sheets-Sheet 1 I I A PRESSURE FLUID E F REGULATOR I B CONSTANT ELECTRO- CONTROL FLUID VOLTAGE RELAY C D I VOLUME TENSION QEELE ,MECHANISM F 2 F 3 O/IQb F loa WIDT 2o THICKNESS MM. 20a

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IZQ- i/IZD INVENTOR. FOREMAN ATTORN Y 1966 A. R. FOREMAN ELECTRICAL TENSION CONTROL DEVICE FOR STRIP PROCESSING LINE Filed Feb. 1, 1963 2 Sheets-Sheet 2 lOa N mA m TM 0% NE W m N T IF :8 R. A E H m B G El 6 b 0 O b b 0 5 2 b R L O L 2 2 0 O o 3 TO GAR S AERLT. S NW H E \D T N a G K m m 0 /W H 3 T AT I 1 United States Patent 3,292,022 ELECTRICAL TENSION CONTROL DEVICE FOR STRIP PROCESSING LINE Archie R. Foreman, Mentor, Ohio, assignor to Production Machinery Corporation, Mentor, Ohio, a corporation of Ohio Filed Feb. 1, 1963, Ser. No. 255,588 5 Claims. (Cl. 31093) The present invention pertains to the art of electrical control devices and more particularly to an electrical device for controlling a mechanism that creates the desired tension in a metal strip passing through a processing line.

Since the present invention is particularly applicable for controlling the tension mechanism of a strip processing line, the invention will be discussed with particular reference thereto; however, it is to be appreciated that the invention has much broader application and may be used to control other mechanisms and devices.

In a processing line for metal strip there is usually provided a mechanism such as a drag brake or floating tension roll, for creating a predetermined tension in the strip so that the strip will be processed uniformly and will travel in a desired path.

The tension in the strip is determined by the crosssectional area of the strip andthe axial or longitudinal force applied to the strip by the tension mechanism. As the area of the strip changes from job-to-job, it is sometimes necessary to change the axial force being applied to the strip so that the tension under which the strip is traveling through the processing line will remain substantially constant. In some job changeovers, even if the cross-sectional area of the strip remains constant, it may be necessary to change the tension in the strip to change the amount of processing to which the strip is being subjected. Accordingly, there is usually provided in such a line an arrangement for controlling the tension mechanism so that the force applied to the strip by the mechanism can be changed in accordance with any change in the cross-sectional area of the strip or with a change in the desired processing.

Many control devices have been proposed to allow adjustment of the force being applied on the strip by the tension mechanism. Consequently, the tension in the strip could be changed or the same tension could be maintained when the cross-sectional area of the strip was changed, These control devices are very expensive, diflicult to maintain and bulky when applied to the processing line. Further, these previous control devices for controlling the tension mechanism could not be remotely located. Accordingly, such control devices had to be positioned closely adjacent the processing line which was often inappropriate because of space limitations.

These and other disadvantages are overcome by the present invention which is directed toward a device for controlling the tension mechanism of a strip processing line which device can easily cause a change in the longitudinal 'force exerted by the tension device onto the strip.

In accordance with the most general aspect of the present invention, there is provided a device for producing an electrical control signal which is proportional to the product of a first and second physical condition. This device comprises an AC power supply, a first autotransformer having input terminals connected to the power supply, output terminals and means for adjusting the voltage ratio of the transformer in accordance withthe first physical condition, and a second autotransformer having input terminals connected to the output terminals of the first autotransformer, means for adjusting the voltage ratio of the second autotr-ansforme-r in accordance with the sec-0nd physical condition and output terminals across which the control signal appears.

By this arrangement, the first and second physical conditions may be the width and thickness of a strip passing through a processing line; therefore, the control signal, which is taken from the output of the second autotransformer, is proportional to the cross-sectional area of the strip and it can be conveniently utilized in controlling a tension mechanism such as a drag brake or floating roll located in the line.

In accordance with a more limited aspect of the present invention, there is provided an improvement in a control device for controlling the tension mechanism of a strip processing line. The improved control device comprises a first autotransformer having input terminals connected to a power supply, output terminals and a means for adjusting the voltage ratio of the transformer in accordance with one transverse dimension of the strip, a second autotransformer having input terminals connected to the output terminals of the first autotransformer, output terminals and means for adjusting the voltage ratio of the second transformer in accordance with the other transverse dimension of the strip, and means controlling the tension mechanism of the processing line in accordance with the voltage across the output terminals of the second autotransformer.

The primary object of the present invention is the provision of a device for producing an electrical control signal proportional to the product of two or more physical conditions, such as, lengths, weight, pressure, etc; which device is very accurate, linear in operation, easy to maintain, and inexpensive to manufacture.

Another object of the present invention is the provision of a device as described above which comprises series connected, back-to-back, adjustable autotransformers with the output of one of the transformers driving the next succeeding transformer so that the output of the second transformer is proportional to the product of the voltage ratios of the individual transformers.

A further object of the present invention is the provision of a device for producing a control signal as described above wherein at least two autotransformers are used and the first autotransformer i manually adjusted so. that the voltage ratio is proportional to the thickness of a strip passing through a processing line the the second autotransformer is manually adjusted so that the voltage ratio is proportional to the width of the same strip. In this manner, the output of the device is an electrical signal adjusted to correspond to the cross-sectional area of a strip passing through a strip processing line which signal can be utilized to change the force exerted on the strip so that the strip is maintained under a desired tension.

Yet another object of the present invention is the provision of a device for producing an electrical control signal proportional to the product of two physical conditions which device includes at least two series connected, backto-back, adjustable autotransformers wherein the voltage ratio of at least one of the transformers can be varied by a transducer so that the output of the device continuously compensates for variations in a physical condition such as length, weight, pressure, etc.

Still a further and more specific object of the present invention is the provision of an improved tension device for controlling the tension on a strip passing through a processing line which improved device is operated by a signal proportional to the width and thickness of the strip and created by a control device including at least two back-to-back adjustable autotransformers.

These and other objects and advantages of the present invention will become apparent from the following description used to illustrate the preferred embodiments of the invention as read in connection with the accompanying drawings in which:

FIGURE 1 is a block diagram illustrating the environment to which the present invention is directed;

FIGURE 2 is a front elevational view of the preferred embodiment of the present invention;

FIGURE 3 is a wiring diagram illustrating the preferred embodiment of the present invention;

FIGURE 4 is a wiring diagram illustrating a modification of the preferred embodiment illustrated in FIGURE 3; and

FIGURE 5 is a combined schematic view and wiring diagram illustrating still a further modification of the preferred embodiment shown in FIGURE 3.

Referring now to the drawings, wherein the showings are for the purpose of illustrating preferred embodiments of the invention only and not for the purpose of limiting same, FIGURE 1 shows, in block diagram, an apparatus for controlling the tension in a strip passing through a strip processing line. The apparatus may assume a variety of structural embodiments; however, in accordance with the illustrated embodiment of the apparatus, there is provided a pressure regulator A for regulating the pressure of a fluid such as air passing therethrough whereby the fluid issuing from the regulator A has a relatively constant pressure; an electro-fluid relay B which accepts the pressure regulated, but unmodulated, fluid from regulator A and modulates the pressure of the fluid in accordance with an electrical signal to be hereinafter described in detail; and a volume booster C adapted to accept, from relay B, a fluid under modulated pressure and combining this modulated pressure fluid with line pressure fluid to produce a modulated fluid output having a higher volume. Further, the apparatus includes a tension control or mechanism D adapted to accept fluid under modulated pressure and high volume from booster C and to convert this modulated pressure into a force which is in turn exerted on a strip (not shown) passing through a strip processing line. To provide the electrical signal that controls relay B, there is included in the apparatus a constant voltage source E adapted to have a substantially constant voltage output and, in series therewith, a control device F having an input and an output 12.

The control device F forms a substantial portion of the present invention, and generally functions by accepting a constant voltage electrical signal from source E and converting this signal into an output 12 which is directed into electro-fluid relay B to control the modulation of fluid from regulator A.

To more fully appreciate the operation of the apparatus illustrated in FIGURE 1, fluid flow which is unmodulated is indicated by the dashed lines, fluid flow which is pressure modulated in accordance with an electrical signal is illustrated by the dotted lines, and electrical control signals are indicated by solid lines.

Referring to FIGURE 2, there is illustrated the preferred embodiment of the present invention wherein the control device F is provided with a front control panel 14 having two dials 16 and 18, the former of which is calibrated into increments of width and the latter of which is calibrated into increments of thickness. In accordance with the present invention as will be hereinafter described in detail, by adjusting dials 16 and 18 the combined voltage ratio of device F, namely, the voltage ratio of input 10 to output 12, is proportional to the product of the readings indicated by dials 16 and 18. If the dials 16, 18 are set to indicate the measurements of a strip passing through a strip processing line, the combined voltage ratio of control device F is proportional to the crosssectional area of the strip. Accordingly, the signal at output 12 can be used to control the output of electrofluid relay B so that the force exerted by tension mechanism D is controlled in accordance with the area of the strip as indicated by setting dials 16, 18. In this manner,

the tension of the strip is easily changed as different strips are processed.

The present invention is specifically directed toward a control device which controls the ratio of the electrical signal in accordance with the cross-sectional area of a strip; however, it is appreciated that'the invention also applies to the combination of the control device and the various components for adapting this control device to use in a tension control for a strip processing line.

Referring now to FIGURE 3, there is illustrated the electrical features of the preferred embodiment of device F, which includes a first adjustable ratio autotransformer 20 having input leads 10a, 10b, corresponding to in put 10 shown in FIGURE 1, and output leads 20a, 20b. The voltage across the output leads is adjustable in accordance with the setting of dial 16 so that the voltage ratio of the transformer 20 is controlled in accordance with the setting of this dial. Also, device F includes a second adjustable ratio autotransformer 22 connected in series with transformer 20 and having an input including input leads 20a, 20b and output leads 22a, 22b. Again, the voltage across the output leads is adjustable in accordance With the settingof dial 18 so that the voltage ratio of the second transformer 22 is controlled in accordance with the setting of this second dial. The series connection of these transformers results in a combined voltage ratio, between leads 10a and 10b and leads 22a and 22b, which is proportional to the product of the settings of dials 16, 18.

In accordance with the illustrated embodiment of the present invention, device F includes a full-wave rectifier 24 which rectifies the output of transformer 22 into a DC. signal across leads 12a, 12b. To adjust the magnitude of the output signal, there is provided, in accordance with the illustrated embodiment of the present invention, a trimming rheostat in one of the output leads, such as lead 12a.

In operation, the control device F receives a constant voltage from A.C. supply E which is applied across leads 10a, 10b and the A.C. signal issuing from leads 20a, 20b is proportional to the product of the setting of dials 16, 18. The magnitude of the DC signal from rectifier 24 is easily adjustable by rheostat 26.

It has been found that the output of device F is a linear function of the settings of dials 16, 18. For instance, if the rheostat 26 is adjusted to provide 58 volts D.C. across leads 12a, 12b when dial 16 is set at 1250 mm. and dial 18 is set at 2.0 mm., if the dial 16 is changed to 625 mm. and dial 18 is changed to 1.0 mm. the output of the device F is 14.5 volts D.C. By further changing the dial 16 to 99.0 mm. while the dial 18 remains at 1.0 mm., the output across leads 12a, 12b is found to be 2.3 volts DC. It is seen that the output of device F is proportional to the product of the width and thickness setting of the dials. By utilizing the output signal of device F, to control tension mechanism D, when a strip having a different cross-sectional area is passing through the processing line, the operator need only adjust dials 16, 18 to the value of width and thickness, and the tension in the strip will be automatically adjusted to the desired value. This is a substantial improvement over known devices for controlling the tension in the strip.

From FIGURES l-3 it is appreciated that the present invention is directed toward the concept of providing a device for producing an electrical control signal proportional to the product of a first and second physical condition such as width and thickness of a strip. The device comprises, in combination, an A.C. power supply, a first autotransformer having an input connected to the power supply, an output and a means for adjusting the voltage ratio of the transformer in accordance with one of the physical conditions and a second autotransformer having an input connected to the output of the first autotransformer, an output and a means for adjusting the voltage ratio of the second autotransformer in accordance with the second physical condition. More specifically, the present invention contemplates such a device for controlling the tension in a strip in a processing line wherein the control device is utilized in combination with a tension mechanism.

The concept of utilizing series connected adjustable autotransformers for producing an electrical signal in accordance with the product of two adjusted values can be utilized in a control device which produces a signal which is the product of more than two adjusted values. Such a control device is shown in FIGURE 4 wherein device G, which is a modification of the embodiment of the invention shown in FIGURE 3, can be utilized to produce an output signal across leads 12a, 12b which is proportional to the width, thickness and desired tension of a strip passing through a strip processing line and this control device includes a third adjustable autotransformer 30 having an input connected to leads 22a, 22b of transformer 22 and output leads 30a, 30b which are connected to the full wave rectifier 24.

The device G as shown in FIGURE 4 can be used in the environment shown in FIGURE 1 and the tension on the strip can be varied by adjusting a third dial (not shown) which would be adapted to control the voltage position of lead 3% of autotransformer 30. In this manner, the width, thickness and tension desired in a strip passing through a line could be dialed into the device G so that a change in the desired tension or a change in cross-sectional area can be separately or jointly dialed with accurate response being realized at the tension control mechnism D.

A further modification of the present invention is illustrated in FIGURE 5 wherein the tension on strip S is controlled by incorporating a position control or transducer H with the three-transformer control device G as shown in FIGURE 4. The control H comprises :an autotransformer 40 having input leads 40a, 40b adapted to be connected to an appropriate constant voltage source as source E shown in FIGURE l, and output leads connected to input leads a, 10b of device G. There is provided an adjustable pointer 42 for adjusting the voltage ratio of transformer 40 which pointer is adapted to be pivoted around a pivot mechanism 44 connected onto a link 46 having a terminal roller 48 adapted to be in contact with a coil 50 from which strip S is payed through work stand 62 and multi-roll leveler 64 driven by motor 66 to pull strip S. Accordingly, as the radius of coil 50 decreases, link 46 and pointer 42 move in the directions of the arrows shown in FIGURE 5 so that the larger the radius of coil 50 the, smaller the voltage ratio of transformer 40. The output of transformer 30 is connected to a drag generator control 52 which is connected through leads 54, 56 an appropriate generator 58 having a mechanical link 60 joining the generator to coil 50. In some cases, it is possible to completely eliminate the rectifier 24 and utilize the A.C. signal issuing from the last autotransformer. This is shown in FIGURE 5 wherein the drag generator control 52 may be controlled by an A.C. signal if desired.

In operation, the generator 58 controls the tension of strip S by varying the drag on the coils. As the radius of the coil 50 decreases, the force exerted by drag generator 58 on strip S increases; therefore, as the radius decreases, it is necessary to decrease the drag of the generator to maintain the same tension on strip S. Accordingly, by providing the device H, the change in radius of coil 50 is compensated for by the adjustment of a fourth autotransformer 40. After adjusting the voltage ratios of transformers 20, 22 and 30, the tension on strip S remains constant with changes in the radius of the coil 50 because of the operation of transformer 40.

It is appreciated that the embodiment of the present invention illustrated in FIGURE 5 could be adapted to use device F shown in FIGURE 3 by providing a means for adjusting the ratio of movement of pointer 42 in accordance with the desired tension of strip S. Although this is possible, the embodiment of the present invention illustrated in FIGURE 5 is preferred because the ope-ration of the dial for controlling the voltage ratio of transformer 30 would be easier to manipulate than a mechanical means for adjusting the movement ratio of pointer 42. If the desired tension were to be fixed, the device H could be easily used with control device F.

The present invention has been described in connection with certain structural embodiments; however, it is to be appreciated that various modifications in the illustrated structural embodiment may be made without departing from the intended spirit and scope of the present invention as defined in the appended claims.

Having thus described my invention, I claim:

1. In a device for controlling the tension on a strip passing through a processing line comprising a tension mechanism for applying an axial force onto said strip and a control means for controlling said mechanism in accordance with the width and thickness measurements of said strip, the improvement comprising: said control means including an A.C. power supply, a first autotransformer having an input connected to said power supply, an output and a first means for adjusting the voltage ratio of said first autotransformer in accordance with one of said measurements, a second autotransformer having an input connected to the output of said first autotransformer, an output, and second means for adjusting the voltage ratio of said second autotransformer in accordance with the other of said measurements, and means for controlling the force exerted by said tension mechanism in accordance with the output of said second autotransformer.

2. In a device for controlling the tension on a strip passing through a processing line comprising a tension mechanism for applying an axial force onto said strip and control means for controlling said mechanism in accordance with the width and thickness measurements of said strip, the improvement comprising: said control means including an A.C. power supply, a first autotransformer having an input connected to said power supply, an output and a first means for adjusting the voltage ratio of said transformer in accordance with one of said measurements, a second autotransformer having an input connected to the output of said first transformer, an output and second means for adjusting the voltage ratio of said second autotransformer in accordance with the other of said measurements, means connecting the output of said second transformer to a rectifier having output leads, and means for controlling the force exerted by said tension mechanism in accordance with the voltage across the output leads of said rectifier.

3. The improvement as defined in claim 2 including a third means for adjusting the output of said control means, said third means including a third autotransformer connected in electrical series with said first and second transformers and a means responsive to a variable condition of the processing line for changing the voltage ratio of said third transformer.

4. A device for controlling the tension on a strip passing through a processing line comprising a tension mechanism for applying an axial force onto said strip and control means for adjusting the tension mechanism in accordance with the width and thickness measurements of said strip, the improvement comprising: said control means including an A.C. power supply, a first autotransformer having an input connected to said power supply, an output and a first means for adjusting the voltage ratio of said transformer in accordance with one of said measurements, a second autotransformer having an input connected to the output of said first autotransformer, an output, and second means for adjusting the voltage ratio of said second autotransformer in accordance with the other of said measurements, means connecting said second transformer to a rectifier having output leads, an adjustable rheostat in one of'said output leads'of said rectifier,- and means for controlling the force exerted by said tension mechanism in accordance with the voltage across the output of said rectifier. r

5. In a device for controlling the tension on a strip passing, through a processing line comprising a tension mechanism for applying an axial force onto said strip and control means for controlling the tension mechanism in accordance with the width and thickness measurements of said strip, the improvement comprising: said control means including an AC. power supply, a first autotransformer having an input connected to said power supply, an output and first means for adjusting the voltage ratio of said transformer in accordance with one of a said measurements, a second autotransformer having an input connected to 'the output of said first transformer, an output, and second means for adjusting the voltage ratio of said second autotransformer in accordance with the other of said measurements and means for controlling the force exerted by said tension mechanism in. accordance with the output of said second transformer, and a second control device for controlling the output of said second transformer in accordance with the desired tension to be applied to said strip, said second control device including a third autotransformer connected in electrical series with said first and second autotransformers and having a third means for adjusting the voltage ratio of said third transformer in accordance with said desired tension.

References Cited by the Examiner UNITED STATES PATENTS 3,097,606 7/1963 Finzel 310-94 X FOREIGN PATENTS 705,179 3/ 1954 Great Britain.

MILTON O. HIRSHFIELD, Primary Examiner.

20 D. X. SLINEY, Assistant Examiner. 

1. IN A DEVICE FOR CONTROLLING THE TENSION ON A STRIP PASSING THROUGH A PROCESSING LINE COMPRISING A TENSION MECHANISM FOR APPLYING AN AXIAL FORCE ONTO SAID STRIP AND A CONTROL MEANS FOR CONTROLLING SAID MECHANISM IN ACCORDANCE WITH THE WIDTH AND THICKNESS MEASUREMENTS OF SAID STRIP, THE IMPROVEMENT COMPRISING: SAID CONTROL MEANS INCLUDING AN A.C. POWER SUPPLY, A FIRST AUTOTRANSFORMER HAVING AN INPUT CONNECTED TO SAID POWER SUPPLY, AN OUTPUT AND A FIRST MEANS FOR ADJUSTING THE VOLTAGE RATIO OF SAID FIRST AUTOTRANSFORMER IN ACCORDANCE WITH ONE OF SAID MEASUREMENTS, A SECOND AUTOTRANSFORMER HAVING AN INPUT CONNECTED TO THE OUTPUT OF SAID FIRST AUTOTRANSFORMER, AN OUTPUT, AND SECOND MEANS FOR ADJUSTING THE VOLTAGE RATIO OF SAID SECOND AUTOTRANSFORMER IN ACCORDANCE WITH THE OTHER OF SAID MEASUREMENTS, AND MEANS FOR CONTROLLING THE FORCE EXERTED BY SAID TENSION MECHANISM IN ACCORDANCE WITH THE OUTPUT OF SAID SECOND AUTOTRANSFORMER. 